Phytoplankton abundance, phycoerythrin concentration and hyperspectral light field data during POLARSTERN cruises ANT-XXIV/4, ANT-XXV/1, and ANT-XXVI/4

Phycobiliproteins are a family of water-soluble pigment proteins that play an important role as accessory or antenna pigments and absorb in the green part of the light spectrum poorly used by chlorophyll a. The phycoerythrins (PEs) are one of four types of phycobiliproteins that are generally distinguished based on their absorption properties. As PEs are water soluble, they are generally not captured with conventional pigment analysis. Here we present a statistical model based on in situ measurements of three transatlantic cruises which allows us to derive relative PE concentration from standardized hyperspectral underwater radiance measurements (Lu). The model relies on Empirical Orthogonal Function (EOF) analysis of Lu spectra and, subsequently, a Generalized Linear Model with measured PE concentrations as the response variable and EOF loadings as predictor variables. The method is used to predict relative PE concentrations throughout the water column and to calculate integrated PE estimates based on those profiles.

藻胆蛋白（Phycobiliproteins）是一类水溶性色素蛋白，作为辅助色素或天线色素发挥关键作用，可吸收叶绿素a（chlorophyll a）难以利用的光谱绿光波段光线。藻红蛋白（Phycoerythrins, PEs）是四类藻胆蛋白之一，通常可依据其吸收特性进行区分。由于PEs具有水溶性，常规色素分析方法一般无法捕获到这类蛋白。本研究基于三次跨大西洋科考航次的原位测量数据构建统计模型，可通过标准化水下高光谱辐射亮度测量（Lu）推导得到相对PE浓度。该模型首先对Lu光谱开展经验正交函数（Empirical Orthogonal Function, EOF）分析，随后以实测PE浓度作为响应变量、EOF载荷作为预测变量，构建广义线性模型（Generalized Linear Model）。本方法可用于预测全水体柱内的相对PE浓度，并基于这些垂直剖面计算PE累计估算量。